I like the name Ella or Ella Brookes! That's good!
I really want to change my name, but I can't choose what to change it to. I've narrowed it down to these: Harley, Brianna, Quinn, Morgan, Ella. Which are your favourites? Would a hyphenated first name and surname be too much? Thanks in advance!
I think Taylor is a nice name, personally I wouldn't change it if I were you. But if you really do I would suggest Hayley instead of Harley.
Quinn is a really nice name and depending on your name I wouldn't change it until you get older.
To be honest, the fact that you are asking the question says that you are not really ready to change your name.
A change of name is a huge step so until you have one name that you really must be called, stick with what you were given. Chances are, if you choose one of these you will decide in a years time that you don't like it.
Your name is fine, why change? Also, have you spoken to your family about it? I know that my family would be upset if I changed the name that they had chosen for me, so be aware - as this could be the case for you too.
In answer to the other part of your question, yes, I do think that a hyphenated first name and last name is too much, one or the other is fine though.